Importance of Accurate Testing

HER2 Testing

Because of Herceptin's (trastuzumab) significant clinical benefits in extending survival for HER2+ metastatic breast cancer patients, it is important to accurately determine the HER2 status of all patients with invasive breast cancer.

How Can I Help To Ensure An Accurate HER2 Test Result?

IHC detects HER2 overexpression at the protein level, and may be affected by conditions of the testing procedures. These include: time to fixation, duration of fixation, processing, denaturation, heating, antigen retrieval, the staining procedure used, and the interpretation of staining.3,7 Although there are antigen retrieval techniques in use, these may result in false-positive IHC results. FISH measures HER2 DNA. Some fixatives, chemicals or heat, may interfere with the FISH assay. However, an internal control is used to distinguish between a FISH-negative and a non-informative result.6 Scoring difficulties associated with FISH testing may be caused by difficulties in identifying specific invasive cells to include in the determination.

HER2 testing should be performed by laboratories with demonstrated proficiency in the specific technology being utilized. Improper assay performance may result from the use of suboptimally fixed tissue, failure to utilize specified reagents, deviation from specific assay instructions, and failure to include appropriate controls for assay validation and can lead to unreliable results. 1,8

Recent findings suggest the need to improve quality control measures in laboratories that use IHC assays, including periodic testing for concordance with FISH. These studies also suggest that large-volume reference laboratories performing HER2 tests are more reliable than small-volume laboratories.3,9 HER2 testing should be done in laboratories accredited to perform such testing. Ongoing proficiency testing is a necessary component of a laboratory's qualification for accreditation.

HER2 test results not always accurate 2

Rate of discordance* between initial test from local lab and subsequent central lab test was assessed in Herceptin adjuvant trial NSABP B-31

Graph: Discordance rates by type of test performed at local lab

*Discordance defined as differing HER2 test result between initial local testing and follow-up central testing as part of quality assurance protocol. Central lab tested IHC by HercepTest and FISH by PathVysion.

  • Certain testing considerations make it inadvisable to rely on a single method to rule out potential Herceptin benefit 1
  • Limitations in assay precision (particularly for the IHC method)
  • Limitations in the direct linkage between assay result and overexpression of the Herceptin target (for the FISH method)

Concordance with central lab correlated with greater testing experience 3

Rates of discordance were lower for labs with greater experience performing the test*

Graph: Discordance rates by lab experience

*Discordance defined as differing HER2 test result between initial local testing and follow-up central testing as part of quality assurance protocol. Central lab tested IHC by HercepTest and FISH by PathVysion.

Labs are required to demonstrate proficiency in specific assays to maintain CAP accreditation 4,5

Collaboration is key among specialists

Collaboration among specialists-including pathologists, surgeons, radiologists, and oncologists-is critical to help ensure accurate interpretation of results and appropriate disease management

Optimal tissue handling requirments4,5

HER2 status should be determined for all cases of invasive breast cancer. The following processes are recommended by ASCO/CAP to help ensure high-quality tissue samples for assays."

  • Tissue acquisition
  • Sections should ideally not be used for HER2 testing if cut >6 weeks earlier
    • This may vary with primary fixation or storage conditions
  • Samples should be sliced at 5-10 mm intervals after appropriate gross inspection and margins designation
  • Tissue fixation
  • Time from tissue acquisition to fixation should be as short as possible
  • Samples should be placed in a sufficient volume of neutral buffered formalin
  • Fixation for fewer than 6 hours or longer than 48 hours is not recommended prior to either FISH or IHC†
  • Time to fixation and duration of fixation, if available, should be recorded for each sample
  • Needle core biopsies
  • Needle core biopsies should not be used for assays if they exhibit:
    • Edge or retraction artifact involving entire core
    • Crush artifact (thin gauge, vacuum extraction needle samples)

†Guidelines allow for needle core biopsies to be fixed for a minimum of 1 hour, but strongly suggest longer fixation times.

Accurate HER2 reporting can prevent therapy delays

A few simple reporting techniques can help expedite treatment with necessary agents for patients with breast cancer.4,5

  1. Clearly indicate patient subscriber number or member identification number on the pathology report.
  2. Identify the specific assay used to assess HER2.
    Include the type of test (IHC or FISH) as well as the specific brand used.
  3. Report HER2 results as quantitative scores.
    Reporting elements for HER2 testing must be standardized. Reports should include the HER2 quantitative results (scores specific to type of assay used) accompanied by the interpretation (positive, equivocal, negative).

see examples below.

Preferred reporting and Examples of reported results
  1. A HER2 result that is equivocal should be reflex tested.
    If the initial assay yields a definitive positive or negative result, that result should be reported. However, if the initial assay yields an equivocal result, a confirmatory test should be completed, and the results of both tests should be reported. If the confirmatory test produces a second equivocal result, the report should indicate that a second assay was completed and specify the quantitative results of both tests (eg, "Equivocal upon reflex to FISH; IHC 2+; HER2/CEP17 ratio=2.1").
  • Adjuvant indications
  • Herceptin is indicated for adjuvant treatment of HER2-overexpressing node-positive or node-negative (ER/PR-negative or with one high-risk feature)† breast cancer:
  • As part of a treatment regimen containing doxorubicin, cyclophosphamide, and either paclitaxel or docetaxel
  • With docetaxel and carboplatin
  • As a single agent following multi-modality anthracycline-based therapy

† High-risk is defined as ER/PR positive with one of the following features: tumor size >2 cm, age <35 years, or tumor grade 2 or 3.

  • Metastatic indications
  • Herceptin is indicated:
  • In combination with paclitaxel for first-line treatment of HER2-overexpressing metastatic breast cancer
  • As a single agent for treatment of HER2-overexpressing breast cancer in patients who have received one or more chemotherapy regimens for metastatic disease

Boxed WARNINGS and Additional Important Safety Information

  • Cardiotoxicity
  • Herceptin administration can result in sub-clinical and clinical cardiac failure manifesting as congestive heart failure (CHF) and decreased left ventricular ejection fraction (LVEF).
    • The incidence and severity of left ventricular cardiac dysfunction was highest in patients who received Herceptin concurrently with anthracycline-containing chemotherapy regimens.
    • Discontinue Herceptin treatment in patients receiving adjuvant therapy for breast cancer and strongly consider discontinuation of Herceptin in patients with metastatic breast cancer who develop a clinically significant decrease in left ventricular function.
  • Herceptin can cause left ventricular cardiac dysfunction, arrhythmias, hypertension, disabling cardiac failure, cardiomyopathy, and cardiac death.
    • In one adjuvant clinical trial, cardiac ischemia or infarction occurred in the Herceptin-containing regimens.
    • Herceptin can also cause asymptomatic decline in LVEF.
  • Cardiac Monitoring
  • Candidates for treatment with Herceptin should undergo a thorough baseline cardiac assessment, including history, physical examination, and an assessment of LVEF by echocardiogram or MUGA scan.
    • Patients should undergo frequent monitoring for decreased left ventricular function during and after Herceptin treatment.
    • More frequent monitoring should be employed if Herceptin is withheld in patients who develop significant left ventricular cardiac dysfunction.
  • Infusion reactions and Pulmonary Toxicity
  • Serious infusion reactions and pulmonary toxicity have occurred; fatal infusion reactions have been reported.
    • In most cases, symptoms occurred during or within 24 hours of administration of Herceptin. Herceptin infusion should be interrupted for patients experiencing dyspnea or clinically significant hypotension.
    • Patients should be monitored until signs and symptoms completely resolve.
    • Discontinue Herceptin for infusion reactions manifesting as anaphylaxis, angioedema, interstitial pneumonitis, or acute respiratory distress
  • Infusion reactions consist of a symptom complex characterized by fever and chills, and on occasion include nausea, vomiting, pain (in some cases at tumor sites), headache, dizziness, dyspnea, hypotension, rash, and asthenia.
    • In postmarketing reports, serious and fatal infusion reactions have been reported. Discontinue Herceptin in all patients with severe or life-threatening infusion reactions.
  • Herceptin use can result in serious and fatal pulmonary toxicity, which includes dyspnea, interstitial pneumonitis, pulmonary infiltrates, pleural effusions, non-cardiogenic pulmonary edema, pulmonary insufficiency and hypoxia, acute respiratory distress syndrome, and pulmonary fibrosis.
    • Such events can occur as sequelae of infusion reactions.
    • Patients with symptomatic intrinsic lung disease or with extensive tumor involvement of the lungs, resulting in dyspnea at rest, appear to have more severe toxicity.
  • Neutropenia
  • Exacerbation of chemotherapy-induced neutropenia has also occurred
    • In controlled clinical trials, severe neutropenia and febrile neutropenia occurred more frequently in metastatic breast cancer patients receiving Herceptin with myelosuppressive chemotherapy compared to chemotherapy alone.
    • The incidence of septic death was not significantly increased.
  • Pregnancy Category D
  • Herceptin can cause fetal harm when administered to a pregnant woman.
  • Post-marketing reports suggest that Herceptin use during pregnancy increases the risk of oligohydramnios during the second and third trimester.
  • Most Common Adverse Events
  • The most common adverse reactions associated with Herceptin use were fever, nausea, vomiting, infusion reactions, diarrhea, infections, increased cough, headache, fatigue, dyspnea, rash, neutropenia, anemia, and myalgia.

Please see the Herceptin full Prescribing Information including Boxed WARNINGS and additional important safety information.

  • References:
  • 1. Herceptin Prescribing Information. Genentech, Inc. March 2009.
  • 2. Data on file. Genentech, Inc.
  • 3. Paik S, Bryant J, Tan-Chiu E, et al. Real-world performance of HER2 testing-National Surgical Adjuvant Breast and Bowel Project experience. J Natl Cancer Inst.2002;94:852-854.
  • 4. Wolff AC, Hammond EH, Schwartz JN, et al. American Society of Clinical Oncology/College of American Pathologists Guideline Recommendations for Human Epidermal Growth Factor Receptor 2 Testing in Breast Cancer. JClin Oncol.2007; 25: 118-145.
  • 5. Wolff AC, Hammond ME, Schwartz JN, et al. American Society of Clinical Oncology/College of American Pathologists Guideline Recommendations for Human Epidermal Growth Factor Receptor 2 Testing in Breast Cancer. Arch Pathol Lab Med.2007;131:18-43.
  • 6. National Comprehensive Cancer Network. Clinical Practice Guidelines in Oncology: Breast Cancer. Version 1; 2007. Available at: http://www.nccn.org. Accessed February 21, 2007.
  • 7. O'Leary TJ. Standardization of immunohistochemistry. Appl Immunohistochem Mol Morphol. 2001; 9:3-8
  • 8. Roche PC, Suman VJ, Jenkins RB, et al. Concordance between local and central laboratory HER2 testing in the Breast Intergroup Trial N9831. J Natl Cancer Inst. 2002; 94:855-857.


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